British light-heavyweight Joshua Buatsi earned a win yet underwhelming start to his career under new promoters with a decision win over Parker in Manchester.
The Olympic bronze medallist's activity level seemingly secured him a majority decision in a close 10-round contest at the Manchester venue.
But Parker had his moments, landing some telling individual punches in a match where the approaches failed to mesh, with excessive holding marring the fight.
The officials had it 96-94 in favor to the winner, with the third a even score.
"It wasn't my finest display but what defines champions? They prevail," Buatsi said in the ring as he was met by negative reactions from the crowd.
The British fighter bounced back after his maiden career setback - an epic battle with his previous opponent in last winter - to secure a 20th pro success.
Some ringside observers felt Parker, 31, deserved the win but the British boxer endured the second setback of his 28-match professional journey.
Buatsi Secures Win in Dull Encounter
His career development has slowed in recent years through management issues and long spells of lack of fights.
Once tipped as the rising talent of UK boxing, he now is positioned trying to realize his potential - perhaps in what feels like a last chance - under new promotional backing.
He started carefully, with neither fighter ready to be aggressive in a tentative early stages.
The challenger, whose only previous defeat came at super middleweight against his former opponent in two years ago after breaking his hand mid-fight, was making just his second bout at light heavyweight.
By the middle rounds, Parker had stayed in contention, creating difficulties for the favorite, who operated with a protective stance to barely take the better periods.
The spectators' acceptance wore thin amid constant clinching, with Parker falling to the floor multiple occasions during close exchanges.
The underdog ended stronger, but multiple periods were difficult to score. However, former world champion Carl Frampton - commentating on the broadcast network - had it strongly leaning for Parker, awarding Buatsi just one round.
Buatsi progresses, but with the likes of hard hitter Benavidez, and Eastern European fighter Bivol ruling the division, the road to world glory - based on this performance - still seems difficult.
Hatton Tribute Motivates Local Rivalry Battle
In the co-main event, Lyndon Arthur beat Rea by split-decision in a excellent local rivalry battle to secure the continental championship.
The stadium grew hushed for a deeply poignant tribute prior to the bout as a bell ceremony sounded in honor of Manchester's own Hatton, who succumbed 46 years old in last month.
It was the initial significant broadcast boxing event in the city since Hatton's death. As the last bell ended, the silence became a shout of "there's only one Hatton".
The competition inside the ropes reflected the emotion. Arthur was knocked down by a powerful punch flush on the chin in the second round, standing uncertainly to his footing on the eight count.
But the Manchester United-red equipment of Arthur soon advanced again. From the other corner, Rea - in rival City blue - was marked up quickly, heavy swelling forming under his eye as the pair landed punishing blows.
The challenger, 27, connected with strong blows but Arthur, 34, fought fire with fire with stinging uppercuts as the action seldom decreased over twelve rounds.
Arthur barely secured the verdict with scoring tallies of draw, 115-113 and 115-112, but the two athletes were relentless and brave, all the qualities their hero Hatton embodied.
